The Influence of Parental Heat-Stress Priming on Drought-Tolerant Maize Progenies’ Field Performance

Maize (Zea mays L.) is a staple crop and an industrial crop. Improving its thermotolerance will be a crucial step in ensuring food security. The objective of this research was to assess the influence of the parental growth environment on their progenies in a non-heat stress environment. The progenies evaluated in this field study were obtained from a 2 × 3 × 3 factorial in a completely randomised greenhouse experiment. Two contrasting growth environments, three maize varieties, and three soil amendments were used in the greenhouse study. A randomised complete block design experiment with three replications was used to grow the progenies. The progenies were examined for nineteen morphological attributes. In this study, 69.51% of the yield variation was explained by the first and second principal component axes. Among the studied attributes, grain weight and cob weight explained more variations in the progenies than the other attributes. The interaction of the parental heat-stress and soil amendment conditions elicited different responses from the drought-tolerant maize progenies. Based on the differences in their yield attributes, the progenies were grouped as poor yielders (Cluster IV), good yielders (Cluster I) and high yielders (Clusters II and III). The parental growth environment influenced the progenies’ field performance in a non-heat-stress environment. Further evaluation of the progenies under a heat-stress environment and molecular analyses are required to establish that a transgenerational effect has occurred.

Association of exopolysaccharide genes in biofilm developing antibiotic-resistant Pseudomonas aeruginosa from hospital wastewater

The study aimed to examine the relationship between antibiotic resistance, biofilm formation and genes responsible for biofilm formation. Sixty-six Pseudomonas aeruginosa isolates were obtained from hospital wastewater and analyzed for their antibiotic resistance. Biofilm production among the isolates was tested by quantitative method crystal violet assay. Biofilm-associated genes among these isolates psl, alg, and pel were also checked. The maximum resistance was observed for ampicillins (88.24%) followed by nalidixic (83.82%), and nitrofurantoin (64.71%), respectively. Biofilm phenotypes are distributed in the following categories: high 39.39% (n = 26); moderate 57.57% (n = 38), and weak 3.0% (n = 2). Among the total isolates, biofilm-associated genes were detected in 84.84% (n = 56) of isolates and the remaining isolates 15.15% (n = 10) did not harbor any genes. In this study, pslB was the most predominant gene observed (71.21%, n = 47) followed by pslA (57.57%, n = 38), pelA (45.45%, n = 30), algD (43.93%, n = 29), and pelD (27.27%, n = 18), respectively. The present study reveals that the majority of the isolates are multidrug resistant being moderate and high biofilm formers. The study implies that biofilm acts as a machinery for bacteria to survive in the hospital effluent which is an antibiotic stress environment.

Fracture Evolution Between Blasting Roof Cutting Holes in a Mining Stress Environment

Blasting roof cutting and pressure relief is an effective technical way to solve the problem of thick and hard roof. In order to solve this problem, it is necessary to carry out research on the evolution of cracks between the cut holes of the blasting roof. The univariate comparative analysis method is used to analyze the evolution law of the fissures between the cuts under different factors. Furthermore, it is concluded that the broken zone and fissure zone of the surrounding rock of the single-hole blasting hole wall are symmetrically distributed in the confining pressure environment, and the fissure zone and the surrounding rock fissure zone between the holes show an "X"-shaped continuous ev olution. By analyzing the evolution law of cracks between blasting holes, the critical discriminant equation of penetration between blasting holes under mining stress environment is given, which is used to optimize the technical plan of blasting roof cutting. Engineering practice shows that the blasting roof cutting scheme has achieved a good seam effect, creating good initial conditions for the cutting of thick and hard roofs.

Water stress intensified the relation of seed color with lignan content and seed yield components in flax (Linum usitatissimum L.)

This study aimed to investigate the effect of yellow and brown seed coat color of flax on lignan content, seed yield, and yield components under two contrasting environments of non-stress and water stress conditions. The water stress environment intensified the discrimination between the two seed color groups as the yellow seeded families had lower values for seed yield components under the water stress. Heritability and the genetic advance for seed yield were significantly higher in brown-seeded families than those of yellow-seeded ones at water stress conditions. Secoisolariciresinol diglucoside (SDG) as the chief lignan in flaxseed was more abundant in yellow-seeded families under the non-stress environment but under water stress conditions, it increased in brown seeded families and exceeded from yellow ones. Considering that the brown and yellow seed color families were full sibs and shared a similar genetic background but differed in seed color, it is concluded that a considerable interaction exists between the flax seed color and moisture stress concerning its effect on seed yield and yield components and also the seed SDG content. Brown-seeded genotypes are probably preferred for cultivation under water stress conditions for better exploitation of flax agronomic and nutritional potentials.

Effects of salt stress on the photosynthetic physiology and mineral ion absorption and distribution in white willow (Salix alba L.)

Objective The purpose of this study was to explore the adaptive mechanism underlying the photosynthetic characteristics and the ion absorption and distribution of white willow (Salix alba L.) in a salt stress environment in cutting seedlings. The results lay a foundation for further understanding the distribution of sodium chloride and its effect on the photosynthetic system. Method A salt stress environment was simulated in a hydroponics system with different NaCl concentrations in one-year-old Salix alba L.branches as the test materials. Their growth, ion absorption, transport and distribution in the roots and leaves, and the changes in the photosynthetic fluorescence parameters were studied after 20 days under hydroponics. Results The results show that The germination and elongation of roots are promoted in the presence of 171mM NaCl, but root growth is comprehensively inhibited under increasing salt stress. Under salt stress, Na+ accumulates significantly in the roots and leaves, and the Na+ content and the Na+/K+ and Na+/Ca2+ root ratios are significantly greater than those in the leaves. When the NaCl concentration is ≤ 342mM, Salix alba can maintain relatively stable K+ and Ca2+ contents in its leaves by improving the selective absorption and accumulation of K+ and Ca2+ and adjusting the transport capacity of mineral ions to aboveground parts, while K+ and Ca2+ levels are clearly decreased under high salt stress. With increasing salt concentrations, the net photosynthetic rate (Pn), transpiration rate (E) and stomatal conductance (gs) of leaves decrease gradually overall, and the intercellular CO2 concentration (Ci) first decreases and then increases. When the NaCl concentration is < 342mM, the decrease in leaf Pn is primarily restricted by the stomata. When the NaCl concentration is > 342mM, the decrease in the Pn is largely inhibited by non-stomatal factors. Due to the salt stress environment, the OJIP curve (Rapid chlorophyll fluorescence) of Salix alba turns into an OKJIP curve. When the NaCl concentration is > 171mM, the fluorescence values of points I and P decrease significantly, which is accompanied by a clear inflection point (K). The quantum yield and energy distribution ratio of the PSⅡ reaction center change significantly (φPo, Ψo and φEo show an overall downward trend while φDo is promoted). The performance index and driving force (PIABS, PICSm and DFCSm) decrease significantly when the NaCl concentration is > 171mM, indicating that salt stress causes a partial inactivation of the PSII reaction center, and the functions of the donor side and the recipient side are damaged. Conclusion The above results indicate that Salix alba can respond to salt stress by intercepting Na+ in the roots, improving the selective absorption of K+ and Ca2+ and the transport capacity to the above ground parts of the plant, and increasing φDo, thus shows an ability to self-regulate and adapt.

Sex-Specific Stress Tolerance in Embryos of Lake Char (Salvelinus umbla)

Salmonid fish have become important models in evolution and ecology, but possible effects of embryo or larval sex are mostly ignored, probably because morphological gonad formation starts only months after hatching and sexual maturation years later. However, recent gene expression studies and first observations in domestic strains suggest that sex-specific life histories could already start at an embryonic stage. Here we test this hypothesis in embryos and larvae of lake char (Salvelinus umbla). We sampled wild char and used their gametes to produce embryos of 40 different families. Embryos were raised singly in a stress or a non-stress environment until a late larval stage (stress was induced by allowing remainders of ovarian fluids to support microbial growth). Genetic markers were then used to sex the fish and reconstruct paternity (N = 1,463, including dead embryos). Primary sex ratio did not differ among families and was about 1:1. Female embryos hatched on average later and showed lower stress tolerance than male embryos. There were significant parental effects on offspring growth and mortality, but the sex differences in embryo performance were not family specific. We conclude that the sexes differ in their life history and susceptibilities to environmental stress already at embryonic stages. Environmental stress during incubation can therefore affect population sex ratio and hence population growth and genetics.

Study on Reasonable Stopping and Time-Sharing Partition Support of Fully Mechanized Top Coal Caving Face Under the Interference of Stopping Line in Close-Up Coal Seam

Close-distance coal seams are widely distributed in China, and there is a problem of stopping mining in a large number of working faces. Taking Yanzishan mine as the engineering background, the mined-out area and the remaining end-mining coal pillar of No.4 coal seam (upper coal seam) mined in advance caused strong interference to the stopping mining of N316 working face of No.3 coal seam under it. Through field observation, laboratory experiment, and support data collection, the mechanical parameters of coal and rock mass and periodic weighting condition of the working face were mastered, and numerical simulation and similar model experiments were carried out. Three positional relationships between the stopping position of the underlying N316 working face and the upper stopping line were obtained: “externally staggered with the upper stopping line” (ESUL), “overlapped with upper stopping line” (OUL), and “internally staggered with the upper stop line” (ISUL, ISUL-SD for shorter internal staggered distances, ISUL-LD for longer ones). The formation and evolution of the stress arch structure of ESUL → OUL → ISUL-SD → ISUL-LD are obtained from the analysis: ① ESUL: there is a double stress arch structure of goaf side and end-mining coal pillar side in the overburden and stress superposition appears in the middle arch foot (stopping mining place). ② OUL: it evolved into a single arch structure of goaf-solid coal, and the stress at the stop of mining was relatively minimum. ③ ISUL-SD: it is still a single arch structure, and the stress at the stop of mining is still small. ④ ISUL-LD: the double stress arch is regenerated and stress superposition occurs at the front arch foot (stopping mining place). At the same time, the morphological evolution process of stress arch is as follows: “front and back stress arches, superimposed with middle arch foot” → “front arch gradually decreases” → “front arch dies, and two arches merge into single arch” → “single arch gradually increases” → “two arches are regenerated, superimposed with front arch foot”. On-the-spot analysis from the combination of stress and overburden structure: ① ESUL: the stress concentration degree is the highest above the stopping space, and the overburden block in the large-scale caving zone directly acts on the support, which makes the stopping operation difficult. ② OUL: although the stress environment is the best, the overlying key blocks will have hidden dangers of overall rotation or sliding instability. ③ ISUL-SD: the stress environment is good, and the overlying rock can realize the stable structure of the cantilever plate (the internal staggered distance is less than the periodic weighting step), and the mining is stopped at this position to realize the safe and smooth withdrawal of the support. ④ ISUL-LD: it is basically consistent with stopping mining when single-layer coal is used but is limited by the limited length of the end-mining coal pillar. In addition, the self-digging retracement channel is designed to serve the whole retracement process, and the idea of time-sharing partition support for a large cross-section of mining stoppage and its corresponding scheme is put forward according to the retracement process. Through the simulation of prestressed field and field practice, the roof overlying rock structure is stable during the whole retracement period, thus realizing the safe and smooth mining stoppage and retracement of the working face.

Plant Gravitropism and Signal Conversion under a Stress Environment of Altered Gravity

Humans have been committed to space exploration and to find the next planet suitable for human survival. The construction of an ecosystem that adapts to the long-term survival of human beings in space stations or other planets would be the first step. The space plant cultivation system is the key component of an ecosystem, which will produce food, fiber, edible oil and oxygen for future space inhabitants. Many plant experiments have been carried out under a stimulated or real environment of altered gravity, including at microgravity (0 g), Moon gravity (0.17 g) and Mars gravity (0.38 g). How plants sense gravity and change under stress environment of altered gravity were summarized in this review. However, many challenges remain regarding human missions to the Moon or Mars. Our group conducted the first plant experiment under real Moon gravity (0.17 g) in 2019. One of the cotton seeds successfully germinated and produced a green seedling, which represents the first green leaf produced by mankind on the Moon.